Plastic base



FIG. 1 is a front view of a plastic base showing my new design;

FIG. 2 is a left view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a perspective view thereof; and,

FIG. 6 is another perspective view thereof.

The broken lines shown in FIGS. 4 and 6 illustrate portions of the plastic base that form no part of the claimed design. 

CLAIM The ornamental design for a plastic base, as shown and described. 